Body fluid homeostasis

Question 1

What is the anti diuretic hormone?

Answer 1

Vasopressin

Question 2

Where is vasopressin released from?

Answer 2

Posterior pituitary gland

Question 3

Where is vasopressin produced? By what?

Answer 3

Produced in the hypothalamus by neurosecretory neurons

Question 4

What is the trigger for a release in vasopressin?

Answer 4

An increase in osmolality

Question 5

Where is the main place in the hypothalamus that vasopressin can be found?

Answer 5

The supra-optic nucleus

Question 6

What are the 2 hypothalamic osmoreceptors?

Answer 6

Supra-optic nucleus
Paraventricular nucleus

Question 7

What stimulates the hypothalamic osmoreceptors?

Answer 7

An increase in osmolality

Question 8

Which substances promotes the release of vasopressin?

Answer 8

Nicotine
Ecstasy

Question 9

What substance inhibits the release of vasopressin?

Answer 9

Alcohol

Question 10

Why can overuse of ecstasy cause death?

Answer 10

Ecstasy promotes the release of vasopressin ->
Body will retain water which is normally secreted ->
Brain oedema due to overload of fluid

Question 11

Where is the V2 receptor found?

Answer 11

Principal cell

Question 12

Describe the vasopressin binding to V2 cascade

Answer 12

Vasopressin binds to V2
->
Activates PKA to phosphorylate vesicles underneath apical membrane
->
Water channels fuse with apical membrane and AQP2 increases

Question 13

What is the net effect of vasopressin binding to V2 receptors?

Answer 13

Increase in water absorption
Decrease in body fluid osmolality

Question 14

How does diabetes insipidus affect vasopressin release?

Answer 14

There is no release of vasopressin (central DI)
Vasopressin is released but is ineffective (nephrogenic DI)

Question 15

Where is aldosterone released from?

Answer 15

Zona glomerulosa layer of the cortex of the adrenal gland

Question 16

What is the role of mineralocorticoids?

Answer 16

Regulates plasma sodium, potassium
Regulates ECF volume

Question 17

How do mineralocorticoids regulate ecf volume?

Answer 17

Via renin angiotensin

Question 18

What does aldosterone act on?

Answer 18

The late distal tubule
Collecting duct

Question 19

What is the cascade of events after aldosterone enters the principal cell?

Answer 19

Aldosterone binds to mineralocorticoid
->
The aldoMR complex stimulates RNA transcription and protein synthesis
->
This promotes opening of Na+ channels, promoting Na+ reabsorption
->
K+ and H+ are secreted

Question 20

What is NPO?

Answer 20

Number of open sodium channel

Question 21

What si the relationship between aldosterone and NPO?

Answer 21

NPO increases as aldosterone increases

Question 22

What happens in an alpha intercalated cell after aldosterone enters?

Answer 22

RNA transcription
Protein synthesis
H+ secretion

Question 23

What is pseudohypoaldosteronism caused by?

Answer 23

Mutations in the mineralocorticoid receptor

Question 24

What does renin angiotensin regulate?

Answer 24

Body fluid volume
Plasma Na+ & K+

Question 25

Where is renin released from?

Answer 25

Juxtaglomerular apparatus (JGA)

Question 26

What is the renin - angiotensin cascade?

Answer 26

When ecf volume decreases, JGA releases renin
->
Renin converts angiotensinogen to angiotensin 1
->
ACE converts angiotensin 1 to angiotensin 2

Question 27

What is the net effect of angiotensin 2?

Answer 27

Increase in Na+, ECFV and Bp

Question 28

What happens when salt is ingested?

Answer 28

Aldosterone is inhibited and Vasopressin is activated